1. Field of the Invention
The invention relates to electric hotplates with a hotplate body having a sealed cooking surface, which is generally made from cast iron and is provided on its underside with heating resistors in the form of wire coils received in ribs in an embedding material (compare U.S. Pat. No. 3,300,621.
2. Description of the Prior Art
The cast iron hotplate body of hotplates of this type is normally surrounded by a pressed-on sheet steel trim ring, which has an inverted U or V-shape. They are fitted into the mounting opening of a mounting plate and the hotplate is braced downwards by a clamp (U.S. Pat Nos. 1,093,754; 2,664,492; British Pat. No. 1,341,753 and, DE-OS 29,09,776). The connection to a power supply is normally by means of screwed-down flexible lines (U.S. Pat. No. 4,348,581). However, hotplates with plug-in connections are also known, which are inserted from above in connector sockets (German Pat. No. 1,021,967).
The underside of this hotplate is covered by a cover plate through which the connection leads are guided by bushings. A second cover plate is provided in a middle area of the first cover plate. Therein the plug connections are mounted in an insulating piece. This arrangement results in a very high cooking hob, which cannot be built-in easily in working surfaces of kitchens.
From U.S. Pat. No. 4,122,330, an electrical hotplate is known which comprises a temperature limiter which is mounted below a cover plate of the hotplate and is also used for housing the hotplate connections.
U.S. Pat. No. 4,658,118, filed on July 10, 1985 and issued on Apr. 14, 1987, shows a quadrangular shaped bushing inserted into a cover plate of a hotplate.
Wide trim rings are known for use in connection with glass cooking hobs, in order to protect the glass plate from the hotplate temperature and for this purpose shielding rings are also provided (U.S. Pat. No. 4,490,603).
Clamps acting in the edge region are frequently used for securing the hotplates (DE-AS 1,130,574; U.S. Pat. No. 3,561,020). In the case of glass mounting plates, the mounting openings are much larger than the diameter of the hotplate body, an accordingly use has been made of centering means and in part by shimmed seals (U.S. Pat. Nos. 3,838,249; 4,491,722 and U.S. Patent application Ser. No. 245,541, filed for on Sept. 3, 1981, in conjunction with Ser. No. 968,048, filed on Dec. 12, 1978 in the name of Karl Fischer and entitled "ELECTRIC COOKER PLATE").
However, it is also conventional practice to use hotplates which do not have a sealed cooking surface and generally comprise spirally wound tubular heaters. These are arranged in optionally interchangeable trays with edges which rest on a mounting opening of a hob. They are connected by means of plugs fitted to the ends of the tubular heaters and these are laterally inserted into connector sockets.